Portable deployable building assemblies must have a foldable capability so that they may be erected where desired and, when necessary, folded up to a compact form for storage and/or transportation. These portable building assemblies utilize struts, which are tubular rods, as the basic construction unit, that form the skeleton structure and thus the configuration of the portable building assembly. The tubular rods noted above are interconnected with one another by some type of movable interconnecting fastening means such as a hub, so that the completed structure is articulated and collapsible. A plastic, canvas or some other type of durable fabric covering is usually applied to the outside and inner surface planes of the tubular rods to envelope the assembly and provide a covered shelter.
An example of such a collapsible structure is shown in U.S. Pat. No. 3,185,164, ('164) which discloses a portable structure having a plurality of rods joined by coupling means into groups of three which are inter-related to form a generally hexagonal structural system. The structure disclosed in '164 employs flexible stays or cables to form the extended shape of the structure and render the structure self-supporting. Another example of such a collapsible structure is shown in U.S. Pat. No. 3,710,806, which employs hub-connected multiply-hinged scissor-type linkages where the linkages articulate allowing the structure to expand or contract. Portable structures that utilize elements which maintain the rigidity of the structure are disclosed in U.S. Pat. No. 3,063,521. Like '164, the structures described in U.S. Pat. No. 3,063,521 employ tension elements such as wires or cables to render the structure self-supporting.
U.S. Pat. No. 3,968,808 ('808) discloses a collapsible self-supporting dome-like structure with a network of pivotal rods interconnected with linking joints. The linking joint holds six rods, each connected to a six-sided metal ring. Each rod is connected onto the ring and is capable of pivoting about the ring. The rod is a permanent attachment and thus cannot be disconnected nor replaced. There does not appear any way to attach a cover to the dome-like structure such as is found in the “keeper” component in the articulating hub assembly of the present invention. Further, the hexagonal ring design described by '808 has six facets, thus offers positions for up to six rods, and the rods must extend radially outward from the linking joint such that rods on opposite sides of the linking joint share a common geometric plane.
U.S. Pat. No. 4,026,313 also discloses a collapsible self-supporting dome-like structure with a network of pivotal rods interconnected with linking joints. The pivotal device linking the rods together forming the structure is a circular joint. Each joint has only four rods which extend radially outward from the joint such that rods on opposite sides of the joint share a common geometric plane. Each rod contains a plug ending with a small cylinder. This small cylinder is nested inside the joint and allows the rod to rotate. It appears that none of the components is easily interchanged. The top and bottom sections of the hubs in the reference appear to be permanently joined by an adhesive so that none of the rods or plugs can be replaced.
U.S. Pat. No. 4,512,097 discloses a display panel mounting clip. The clip body is used to connect display panels together. The clip assembly disclosed requires a spring mechanism to create tension and hold the panels together. The present invention requires no springs. The clip disclosed in the reference must be snapped into an opening joining the rods in a circular joint. In the present invention, the circular hub is screwed into the hub section so it is threadedly secured.
U.S. Pat. No. 4,280,521 discloses a hub assembly for collapsible structures. The hub assembly disclosed in the reference requires a circular retaining ring to hold the “column like elements” or tubes in place. Each tube must be threaded onto a circular retaining ring prior to insertion into the hub section. The tubes are arranged such that tubes on opposite sides of the hub rotate within the same plane. In the hub disclosed in U.S. Pat. No. 4,280,521, the hub sections are secured in place by use of an adhesive to fuse the two hub sections together permanently. The tube members within the structure, therefore, are not easily replaceable since the hub sections cannot be replaced without destroying them.
In the present invention no circular ring is present or required to hold the rods together inside the hub to allow rotation. The present invention as explained in detail hereinafter, requires that each tube have its own tang, each with its own roll pin to independently nest inside the hub body, thus no ring is present. It is an object of the present invention to provide a hub assembly that has the capability of quickly and easily removing the strut which is contained within the hub.
The U.S. Pat. No. 4,280,521 design, described above, uses a three piece clamping device to hold or attach a skin or cover to the structure. One piece is a plug that is incorporated inside the hub section and is fused into the hub sections. The second piece is a flat disc. The third piece is an element which is a screw. The screw is threaded into the plug and holds the clamp down. A screw driver would obviously be required to remove the clamp if or when the cover, the skin or the tubes have to be replaced.
Soviet Patent No. 1,392,220 discloses a joint between rods which possesses two pressure plates whose surfaces face each other and have spherical loons with slits from each loon to the outer outline of the pressure component plate. Screws appear to join the upper plate with the lower plate to hold the ball joints in place. The reference does not disclose a hub assembly such as described and claimed herein.
Collapsible frame structures for supporting tents or other outdoor shelters are disclosed in U.S. Pat. Nos. 563,376; 927,738; 1,773,847 and 2,781,766. These structures do not possess the improved hub of the present invention to allow the flexibility found in the structures using the hub of the present invention. Other collapsible structures disclosing some form of connecting means to hold the tubular rods in place are described in U.S. Pat. Nos. 3,968,808; 4,026,313; 4,290,244; 4,437,275; 4,473,986; 4,512,097; 4,522,008; 4,561,618; 4,579,066; 4,607,656 4,641,676, 4,689,932, 4,761,929, 4,779,635 and 4,838,003.
The typical prior art structures disclosed in the references cited above suffer from a common problems. With respect to the collapsible structure, due to the immense size which is needed in many present military and civilian applications, it is often difficult to erect (i.e., to raise or to lower) the skeleton structure. The inherent difficulties are that to erect or to collapse the structure requires several workers, takes a significant amount of time, and requires special tools and equipment. In addition, in the collapsed state, existing structures are too large. Thus the structures are bulky and heavy and have a complicated construction. The deployable portable building assemblies must be capable of being collapsed quickly an easily folded up into a compact structure.
The type of building assemblies using the hub disclosed in U.S. Pat. No. 5,797,695 ('695) to A. Jon Prusmack conveniently collapse to a bundle having a cylindrical configuration along its longitudinal axis when stored.
Cross sectional representation of the outline of the perimeter of an example of the structure disclosed in the '695 patent is depicted in FIG. 1A with five “sections” or “quads” using a specific and small diameter tubular rod. FIG. 1B represents the perimeter of the shelter of present invention and depicts seven “quads”, I through VII using a much larger diameter tubular rod have side and diagonal elements formed from tubular strut elements connected at each end and in the center to a hub. Practical and structural considerations limit each of the five sections found in the '695 prior art structure to 5 feet square. Thus the structure in the embodiment depicted in FIG. 1A has a maximum horizontal distance between quad 1 and quad 5 of 11.75 feet. The limitations stem from the design of the hub where the rods on opposite sides of the hub share the same geometric plane, thereby limiting the diameter of the rods to 0.5 inches if acceptably compact collapsed structures are to result. The limitations on the size of the structure result from structural properties of practical 0.5 inch diameter rod and structural requirements of erected structures.
In order to function efficiently, the dimensions of each of the rectangular sections comprising the structure must be suitable to allow the structure to be erected speedily as well as allowing the structure to be collapsed speedily.
As noted above, each of the quads of the commercially efficient deployable structure, as contemplated in the '695 patent as depicted in FIG. 1A, possesses tubular strut elements that together with the hubs measure about 5 feet in length and width. The diameter of the prior art tubular strut elements contemplated by the '695 patent is about ⅝″ (0.625″). These length/diameter dimensions allow the tubular rods of the structure to be collapsed into the cylindrical configuration noted above. Using the 5 feet quad dimensions and the tubular strut of ⅝″ diameter, when the structure is erected, the distance from the ground to the center point of quad 3 of FIG. 8.25 feet.
When attempting to construct a portable building assembly having greater height, width and length dimensions compared with the '695 assembly, it was determined that serious problems were encountered with the structural integrity of the shelter.
In the situation in which one is forming a larger deployable structure than that enabled by the '695 patent, a larger, stronger tubular strut would be required than the existing struts having a diameter of ⅝″. The larger diameter strut using the same size hub as disclosed in the '695 Patent will not produce a shelter possessing the required features necessary for prompt tactical deployments. An increased diameter strut (i.e., greater than ⅝″), used in combination with the prior art hub, will not collapse to an adequately compact bundle when collapsing the structure. Accordingly, the structure cannot be folded to possess the required volume in the collapsed state or “low racking volume.”
If one desires to construct a larger shelter unit as depicted in FIG. 1B, having a height, for example, of 18 feet up to 32 feet, and accordingly a wider horizontal space between the sides I and VII , the additional stress on the tubular struts in the expanded structure of the assembly as well as other factors must be considered. The increased building dimensions does result in increased weight. If one opts to increase the diameter of the tubular struts comprising the quads in the construction of a larger deployable shelter to compensate for the increase in stress resulting from the wider span and added weight, substantial construction problems result. If the tubular strut is increased to, for example, 7 feet, the complementary angles between sections I and II, II and III and III and IV, etc. will be changed, so the symmetry which is inherent in the '695 prior art shelter is lost and the structure is totally different and unsuitable for the required prompt set-up and fold-up.
In my copending application, Ser. No. 11/228,651 certain basic features of articulating hub assemblies are also disclosed. As noted, that application is incorporated by reference herein.